The present invention, in some embodiments thereof, relates to a materials dispenser and, more particularly, but not exclusively, to devices for dispensing liquids, pastes, foams, and the like, under pressure.
Aerosol spray cans are known throughout modern society, and are used in myriad products found in food stores, pharmacies, tool shops, and more. Fire extinguishers also provide a stream of material under pressure.
Aerosol canisters typically deliver material pressurized to seven or eight bars. A few methods are popular. Single Compartment methods mix a deliverable material with a propellant (a compressed gas), and spray both through a valve. Dual Compartment methods separate the deliverable material from the propellant to avoid interaction between them, to increase shelf life of the product, and for various other reasons. Some Dual Compartment methods use a bag for deliverable material. Some separate material from propellant using a piston barrier. In both cases a compartment with a pressurized propellant is used to pressurize a compartment with a deliverable material, which can then be delivered under pressure through a valve. Practical considerations and in some jurisdictions also laws and regulations require that containers for aerosol products using a propellant (typically compressed to 7-8 bars) to be cylindrical in format, for safety reasons. Containers are also required to be metal or of thick glass or of rigid plastic, or in any case to be of sufficient strength and thickness to safely withstand this pressure. If made of metal other than aluminum (which is relatively expensive), containers are usually made out of TinPlate and coated with lacquers or other coatings to prevent them from rusting and releasing the pressure in unintended ways. As a result, aerosol containers are often relatively expensive to make, to transport, and to handle in bulk, are constrained to be in a standard shape, and are difficult to dispose of in an ecologically desirable manner.
For low pressure dispensing applications, the state of the art is generally that users use manual pressure to pump or squeeze products from containers, for example to get food and suntan lotion out of plastic squeeze bottles, or to get toothpaste and pharmaceuticals out of collapsible tubes, or press on a mechanical pump to deliver the product. In addition to the potential inconvenience attached to the use of many such packages, they suffer from the additional potential disadvantage that air entering such packages interacts with the material therein, reducing shelf life. An additional possible disadvantage is that it is often difficult or impossible to empty them completely, leading to either a messy operation or wastage of products, frustration of users, and/or unnecessary expense.
The following patent documents may be relevant to this field.                U.S. Pat. No. 4,121,737: Apparatus for pressure dispensing of fluids        WO9509784: Package as dispenser for a pressurized fluid substance        U.S. Pat. No. 4,222,499: Pressurized fluid dispensing apparatus having expansible bladder held in place with compressive forces        DE102004028734: Environmentally friendly aerosol especially for cosmetic applications has the contents held in an elastic inner liner which contracts to expel the charge without any pump or propellant        U.S. Pat. No. 5,127,554: Aerosol power system        WO2004080841: Spray device        U.S. Pat. No. 2,966,282: Dispensing package for fluids        GB2209056: Liquid container        WO0115583: Food Container        U.S. Pat. No. 3,981,415: Dispenser with expansible member and contracting fabric        EP0248755: Pressurized container        FR2608137: Device in the form of a container of fluid or powder packaged under pressure to facilitate its self-ejection or controlled self-outflow        US2009045222: Bag of variable volume, device suitable for dispensing fluids        US2006243741: Aerosol can        GB2278823: Liner for dispensing container        U.S. Pat. No. 4,077,543: Propellantless aerosol container        FR2707264(A1): Device for dispensing a substance and system adapted for filling the latter        U.S. Pat. No. 3,791,557: Non-aerosol container with expansible bladder and expelling force providing sheath        U.S. Pat. No. 5,111,971(A): Self-pressurized container having a convoluted liner and an elastomeric sleeve        U.S. Pat. No. 4,251,032: Appliance for discharging gaseous, liquid or pasty product, and process of its manufacture        U.S. Pat. No. 5,927,551: Power assembly apparatus        U.S. Pat. No. 4,964,540: Pressurized fluid dispenser and method of making the same        U.S. Pat. No. 5,060,700: Dispenser for a viscous substance        U.S. Pat. No. 4,981,238: Dispensing can for viscous substances        WO/2010/145677        WO/2010/085979        